In the U.S. Congress, legislation is initiated in either the House of Representatives or the Senate. Revenue, appropriations and tax bills, however, must originate in the House.
Assume your House of Representatives member has an idea for a new law. He or she writes the bill and becomes the chief sponsor of that bill. The bill is then assigned a number that is effective for the current session of Congress (two years) and then it is introduced. "H.R." designates bills introduced in the House and "S." designates bills introduced in the Senate. Any bill not passed and enacted into law by the end of the second session in Congress, "dies" and must be reintroduced in the next Congress.
After the bill is introduced in the House, it is assigned to a committee. In the House it goes to one of 22 standing committees, each with jurisdiction over bills in a certain topic area. The Chairman of the standing committee or subcommittee to which a bill is referred decides which bills will be considered and which bills will not receive action; most bills die in committee. If the bill moves forward, a subcommittee will hold hearings to collect testimony from experts and persons with interest in the bill. The subcommittee and the full committee may hold a markup session in which amendments are offered to the bill. Once that is done, the committee will hold a vote to kill it or vote the bill out of committee (which is often referred to as "reporting the bill").
When a bill is reported out, it goes to the full House for consideration. At this stage of the process the Rules Committee plays an important role. The Rules Committee decides how much time will be devoted to debate, and which, if any, amendments may be offered. Non-controversial bills that do not cost much may move through the House, bypassing the Rules Committee in a process known as "suspension of the rules." Under suspension of the rules, a bill must receive support from two-thirds of the members voting to pass. Most other bills require only half the members present to vote for it to pass.
In the Senate, after a senator introduces a new bill, it is assigned to one of the 16 standing committees. The Senate committee may study and amend the bill and then either release or table the bill. Like in the House, only a few bills are taken up for a vote in the full Senate.
Once released, the bill goes to the Senate floor for consideration. The Majority Leader of the Senate determines which bills will be considered and the order in which they are debated. Since the Senate does not have a Rules Committee like in the House, the Majority Leader and the Minority Leader generally work together to determine how the bill will be considered and if the bill will require half the members to vote for it, or three-fifths of the members. In the Senate, because of the filibuster rule, it may require 60 votes, or three-fifths of the full Senate to get a bill passed.
A bill that has been passed by both the House and Senate moves to a conference committee, which is made up of members from each chamber. The committee works out any differences between the House and Senate versions of the bill. The revised bill is sent back to both chambers for their final approval. Before a bill can be sent to the President, it must pass both the House and Senate in identical form.
The bill then is sent to the President for action:
Most state governments operate in similar fashion, although each state has its own unique process for how and when bills may be introduced and considered, and what responsibilities the Governor has in the process.